1. Field of the Invention
The present invention relates to an image reading apparatus.
2. Description of the Related Art
Conventionally, in an image forming apparatus, an original conveying system of an image reading unit that conveys an original and reads an image of an original being conveyed, and a recording material-conveying system of a printing unit for conveying recording materials are constructed independently of each other.
More specifically, the original conveying system and the recording material-conveying system are each provided with a sheet feeder for feeding originals or recording materials, a sheet feeder unit, guiding members forming predetermined conveying paths, and so on, independently of each other. Further, the original conveying system and the recording material-conveying system are each provided with a plurality of conveying roller pairs, a drive force transmission unit for transmitting a drive force to the plurality of conveying roller pairs, a motor as a drive source, a drive circuit of the motor, a sheet discharging section, and so on.
For this reason, it is inevitable that the entire mechanism construction of the image forming apparatus has become increasingly complex and the cost and size of the apparatus have been increased.
To solve this problem, there has been proposed an image forming apparatus in which an image reading unit is provided in a recording material-conveying path extending from a sheet feeder to a sheet discharger, thereby forming respective sections of the original conveying system and the recording material-conveying system as a section which can be shared between them, to thereby attain reduction of the size of the image forming apparatus (see e.g. Japanese Patent Laid-Open Publication No. 2000-185881).
However, the image forming apparatus disclosed in Japanese Patent Laid-Open Publication No. 2000-185881 has the image reading unit arranged in an intermediate portion of the recording material-conveying path e.g. between a fixing device and the sheet discharger, and hence the path for conveying an original to be read becomes long. This configuration makes it difficult to reduce time for reading the original.
Further, the image reading unit is provided in the recording material-conveying path used for usual printing, and hence when an original stays in the recording material-conveying path, the print operation cannot be performed. Therefore, the print operation has to be stopped during the operation for reading the original.
Further, not only an original but also a recording material passes an original reading surface of the original reading unit, and hence the reading surface is liable to get soiled, and what is more, time to perform correction of the original reading unit is limited.